Feed supplements and methods for the preparation thereof

ABSTRACT

A feed supplement, e.g., an animal feed supplement, is prepared by a method comprising treating whey, for example, from the manufacture of cottage cheese or cheddar cheese, with a bisulfite moiety to react the lactose present in said whey and form a lactose-bisulfite addition product. The lactose-bisulfite addition product is more soluble in water than lactose; therefore, the treated whey may be condensed by removing water therefrom, without sedimentation of the lactose during condensation or upon storage. The condensed whey may be mixed with a source of nutrients to provide a full ration animal feed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to feed supplements and particularly to themanufacture of animal feed supplements comprising condensed wheyproducts.

2. Background of the Art

Whey, a by-product of the cheese manufacturing process, is the aqueoussolution remaining after the cheese is separated from the cultured milk.Whey contains various nutrients, including proteins, calcium salts,phosphate salts, and lactose. The large volume of whey that results fromcheese manufacture represents a serious disposal problem. Lactose, themain ingredient in whey, causes the major problem of disposing of whey.In particular, whey can not be disposed of as sewage since lactose is acarbohydrate and can be utilized by various undesirable microorganismsfor growth.

Whey is an obvious source of nutrients for animals and humans as well asmicroorganisms. However, it must be condensed by removing water to makeit economical for use as a nutrient. For example, it is economicallydesirable to condense whey to about 40 percent dissolved solids, byweight, to avoid handling and shipping of large amounts of water. Thesolubility of lactose in water is only about 18 percent, by weight, at25° C.; therefore there is a problem, for the lactose tends toundesirably sediment out of the condensed whey.

It might appear to be a simple matter (if one desired to obtain usefulproducts by condensing whey) to allow the lactose crystals toprecipitate from the condensed whey to recover both a solid lactose anda condensed whey which would not be subject to further lactosesedimentation. Lactose, however, has the tendency to form supersaturatedsolutions. Therefore unless long standing times can be tolerated,lactose continues to crystallize after the crystals of lactose arefiltered from the supersaturated filtrate. The resulting heterogeneouscondensed whey product is difficult to handle and as a result the simpleremoval of water to provide a condensed whey has not found commercialfavor.

Condensation of whey and spray drying of the resulting condensate toprovide a solid material for use in the food industry has also beenattempted. The above noted insolubility of lactose in condensed wheysolutions results in sedimentation during condensation and fouling ofthe heat exchange surfaces of the water removal devices by the sediment.

Many have tried to treat whey by methods other than condensation torecover useful products and avoid the problems of disposal. For example,ultrafiltration has been applied to whey to separate the lower molecularweight materials from the protein with the object being to isolate thefractions of whey and thus obtain more valuable products. Theultrafiltration of whey has been found to be uneconomic.

It has been proposed that, prior to condensation, the lactose in whey behydrolyzed with mineral acid to yield lower sugars which are moresoluble than lactose. However, even though lactose may be efficientlyhydrolyzed with acid, the necessary requirements of heat, acid and timemakes this process uneconomical.

Enzyme hydrolysis of the lactose to lactic acid or glucose and galactosehas been utilized to provide a whey that does not separate uponcondensation and storage. This process requires no heat input; however,the cost of the enzyme imparts an unacceptable economic burden on theprocess.

Finally, the treatment of whey with alkaline materials to eithercoagulate the proteins or convert the lactose in whey to the moresoluble lactulose has been suggested. It is found, however, that thealkaline treatment tends to degrade whey and therefore the product maylose some of its value as a food or nutrient. Recent processes, whichutilize alkali treatment in combination with various complexing agentssuch as aluminates, borates (or boric acid), and/or treatments withtrialkylamines (with or without boric acid), have been applied tominimize alkali degradation and optimize conversion of lactose to a moresoluble isomer, i.e., lactulose. In each of these processes, however,the reactants utilized in the conversion of lactose to lactulose must beremoved from the reaction product prior to use as an animal feed. Forexample, the boron from the boric acid reactant must be carefullyremoved because of its poisonous nature. Excessive aluminum alsointerferes with the proper assimilation of phosphorus, calcium andmagnesium by an animal and, therefore, while not poisonous must beremoved as well.

Thus it is one object of the invention to provide a whey condensatewhich does not sediment upon storage for long periods of time and/or atless than ambient temperatures.

It is another object of the invention to provide a whey condensate whichdoes not have to be post treated to remove reactants or reactionproducts utilized in the solubilization of the lactose contained in thewhey.

It is another object of the instant invention to provide a condensedwhey which is suitable for blending with other sources of nutrients toprovide a full ration animal feed.

It is another object of the invention to provide a condensed whey whichis stable to fermentation and spoilage caused by microorganisms while instorage.

It is another object of the invention to provide a condensed whey whichis useful for stabilizing blends thereof with other nutrient sourcesagainst spoilage.

It is another object of the invention to provide a blend of condensedwhey and another source of nutrients having a high moisture content thatis stable during storage.

It is another object of the invention to provide a treated whey that canbe condensed without sedimentation of lactose therefrom.

Other objects and advantages of the invention will be apparent from thefollowing specification.

SUMMARY OF THE INVENTION

The invention provides a method of inhibiting the crystallization orprecipitation of lactose from whey which comprises contacting the wheywith a bisulfite moiety, e.g., sodium bisulfite, to form a noveladdition product of lactose and bisulfite. After formation of theaddition product, water may be removed to yield a condensed whey whichis stable against sedimentation during storage for long periods of timeand/or at temperatures below ambient.

The condensed whey product described above may be blended with othersources of nutrients such as molasses, fibrous roughage, grain,non-protein nitrogen, minerals, vitamins, etc. to provide a full rationanimal feed. The condensed whey product can also be used itself for itsnutrient value since it is a source of both protein and carbohydrates.However, due to the inclusion of the bisulfite moiety, the condensedwhey may not be as palatable as would be desired. Therefore, blendingwith another nutrient source to dilute the effect of the bisulfite onpalatability is usually preferred. On the other hand, the inclusion ofthe bisulfite moiety (either as the lactose-bisulfite addition productor as excess bisulfite) in condensed whey acts to retard spoilage bymicroorganisms during storage. Thus, a further advantage provided by thecondensed whey of the instant invention is that at a level of bisulfitesufficient to solubilize the lactose, the condensed whey, itself,imparts stability from microorganism spoilage to blended products.

DETAILED DESCRIPTION OF THE INVENTION

It has now been found that whey, which has a tendency to crystallizeupon condensation, may be stabilized against such crystallization bytreatment with a bisulfite moiety at conditions sufficient to convertlactose (the major component of whey) into a lactose-bisulfite additionproduct. The bisulfite treated whey may be condensed by removal of waterat atmospheric pressure or under vacuum conditons to yield a condensedwhey product containing at least about 35 percent and more preferablyabout 40 to about 50 percent, by weight, solids. The condensed whey maybe utilized directly as an animal feed supplement or can be blended withanother source of nutrients to provide a full ration animal feed.

More particularly, whey which may be obtained from the process for themanufacture of cheese, caseine whey, partially delactosed whey, and thewhey filtrate obtained by the ultrafiltration of whey solutions or skimmilk may be mixed with an aqueous solution including a bisulfite moietyat conditions suitable to react the lactose in the whey with saidbisulfite moiety to form the addition product thereof. The bisulfitemoiety may be provided by any suitable water-soluble salt containingsaid bisulfite moiety. For example, the ammonium, alkali metal andalkaline earth metal bisulfite salts are useful for providing thebisulfite moiety. The sodium bisulfite or the ammonium bisulfite salt ispreferred for providing the bisulfite moiety due to the relativeavailability and cost of each. However, ammonium bisulfite is especiallypreferred since it provides an additional nutrient nitrogen in thecondensed whey.

Alternatively, the bisulfite moiety can be obtained by passing SO₂ as agas through a whey solution to generate the bisulfite in situ. The pH ofthe whey may first be adjusted with a base, e.g. NaOH, Ca(OH)₂, NH₄ OH,etc. prior to passage of SO₂ therethrough to assist in solubilizing theSO₂ therein. Moreover, it is convenient to pass NH₃ through the wheysimultaneously with or prior to the SO₂ to generate in-situ ammoniumbisulfite.

The reaction of the bisulfite moiety and the lactose is substantiallycarried out on at least a stoichiometric basis although lesser amountsof bisulfite can be utilized to provide at least partial solubilizationof lactose. Moreover, with excess bisulfite, the lactose-bisulfiteaddition product will not decompose to lactose if the bisulfite (as SO₂)is removed during storage. The excess bisulfite tends to inhibitspoilage by microorganisms during storage, and, therefore, an excess ofbisulfite has certain advantages. For economy, it is preferred that anexcess of no more than about 0.2 moles of bisulfite is provided for eachmole of lactose in the whey.

The reaction may be carried out at any temperature at which the whey isliquid, e.g., such as at a temperature of about 30° F. to about 200° F.Since whey is available from the manufacture of cheese at a temperatureof about 100° to about 150° F., this temperature range is convenientlyutilized for the reaction whereby cooling of the whey solution may beavoided.

The reaction is usually carried out at ambient pressure conditions forconvenience, however, it may be desirable to carry out the reaction atelevated pressures if the gaseous SO₂ is utilized as the bisulfitemoiety to ensure increased solubility of SO₂ in the whey. Furthermore,condensation can be effected while the bisulfite reaction is takingplace by carrying out the reaction under vacuum conditions andpreferably while providing heat to assist in the removal of water.

The condensation of the whey is generally effected by heating thebisulfite-treated whey to an elevated temperature under vacuum to removesufficient water to provide a condensed whey having at least about 35percent and preferably from about 40 to about 50 percent solids, byweight. Alternatively, one might also condense the whey prior totreating with the bisulfite moiety provided that the condensationprocess is monitored to avoid excessive crystallization of lactose.

The preferred bisulfite-treated whey product after condensation ischaracterized as having at least about 1.0 percent sulfur and morepreferably at least about 2 percent sulfur, e.g. 2 to 3 percent sulfur,by weight. This novel condensed whey will also comprise at least about30 percent by weight lactose as the bisulfite addition product. Theother solids include the other components of the whey prior tocondensation and reaction with bisulfite moiety, e.g., proteins, calciumand phosphate salts, etc. The product may have an odor of SO₂,indicating that there may be some free SO₂ dissolved therein. The freeSO₂ can be removed if-desired, by heating or adjusting the pH toneutralize the SO₂. However, since SO₂ acts as a preservative againstspoilage by microorganisms, it is generally retained as is. The productis somewhat unpalatable due to the SO₂ content and therefore may beblended with molasses or other by-product liquors to provide a morepalatable animal feed supplement.

The condensed whey of this invention may be combined with various othernutrient sources to provide a full ration animal feed. For example, in aconfined feed lot, a dressing agent including the condensed whey of thisinvention in combination with one or more other carbohydrate-containingby-product liquors such as molasses (including blackstrap, invertedblackstrap, inverted sugar-beet), hydrol syrup, wood-sugar syrup, citrusmolasses, condensed distillers molasses solubles, refiners molasses,etc., which carbohydrate-containing liquor may be ammoniated orhydrolyzed with acid; may be combined, usually at a level of from about5 to about 10 percent, by weight, with various sources of roughage, suchas chopped corn sileage, hay, etc; non-protein nitrogen, such as urea,ammonia, etc.; minerals, such as calcium, phosphorus, sulfur, iron,zinc, manganese, copper, cobalt, etc; vitamins such as the oil-solublevitamins, A, D and E; grain, such as barley, wheat bran, crushed oats,cracked corn, etc.; and natural protein, such as soybean meal,cottonseed meal, fish meal, bone meal, blood meal etc., to provide afull ration animal feed. The grain and roughage may comprise about 50 toabout 90 percent, by weight, of said full ration animal feed, with theweight ratio of grain to roughage varying from about 1 to about 0.1. Alower ratio of grain to roughage is preferred in situations where arapid increase in weight is desired.

The invention is further illustrated by the following example which isillustrative of a specific mode of practicing the invention and is notintended as limiting the scope of the appended claims.

EXAMPLE 1

A sample of a previously condensed whey comprising 45 percent solids andhaving a dispersed phase comprising lactose crystals is heated to 150°F. and held at that temperature for one hour until the crystalsdissolve. The resulting homogeneous solution is held at 150° F. andincreased amounts of sodium bisulfite are dissolved therein. (The sodiumbisulfite is dissolved directly in the heated solution.) An aliquot ofthe bisulfited whey solution is taken after each addition of sodiumbisulfite and such aliquot is allowed to cool to room temperature (i.e.about 65° F.) and stand for two days. The cooled aliquots arecentrifuged to determine volume of sediment. The results are summarizedin table 1 below:

                  TABLE 1                                                         ______________________________________                                               gm NaHSO.sub.3                                                         Sample 100 gms Condensed Whey                                                                          % Volume Sediment                                    ______________________________________                                        1      0                 31-35                                                2      2.5               22-27                                                3      5                 13                                                   4      7.5               0.5                                                  5      10                0.1                                                  ______________________________________                                    

It is noted that the control shows a crystallization sedimentapproximating 1/3 of the total volume of the aliquot. After two days'standing, the aliquot having 5 grams of sodium bisulfite per hundredgrams of solution shows only 13 percent sedimentation by volume.However, when 7.5 grams of sodium bisulfite per hundred grams ofsolution (and greater) are added to the solution substantially nosedimentation occurs upon standing.

Each of the aliquot samples has a slight, free-SO₂ odor. Therefore, a pHadjustment of sample 3 is made to determine whether the formation of thelactose-bisulfite addition product is pH dependent. (The pH of thecondensed whey is about 4.6). Sample 3 is divided into three samples andthe pH is adjusted upward with a 25 percent, by weight, solution ofsodium hydroxide in water to provide samples having a pH of 5, 6, and 7.The pH adjusted samples are stirred for one hour. It is found that noneof the samples shows a decrease or increase in sedimentation, thusdemonstrating that the formation of the lactose-bisulfite additionproduct is independent of pH in this range.

Moreover, although an acid pH tends to convert some of the bisulfite toSO₂, the preservative effects of SO₂ are useful in the products preparedby the instant invention and, therefore, an acid pH in the condensedwhey is preferred. The tendency of the addition product of lactose andbisulfite to convert to SO₂ at an acid pH also results in the novelproducts of this invention being useful preservatives when combined withacidic feedstocks.

EXAMPLE 2

The procedure of example 1 is repeated except that potassium bisulfiteis substituted, at an equivalent molar concentration, for sodiumbisulfite. As with example 1, the volume of sediment upon standingdecreases as the concentration of dissolved potassium bisulfite isincreased.

EXAMPLE 3

The procedure of example 1 is repeated except that SO₂ gas is passedthrough the heated whey solution (after addition of a soluble base) toprovide the equivalent concentrations of bisulfite dissolved therein. Aswith example 1, the volume of sediment, upon standing, decreases as theconcentration of the bisulfite in the condensed whey increases.

EXAMPLE 4

The procedure of example 3 is repeated except that gaseous ammonia issimultaneously passed through the heated whey solution to provideadditional nutrient nitrogen to the resulting bisulfited whey products.The volume of sediment in the resulting products upon standing issubstantially similar to the volume of sediment of the bisulfited wheyproducts of example 3. Moreover, when an equal concentration of ammoniais dissolved in the whey prior to addition of SO₂, similar results areobtained.

While particular embodiments of the invention have been described itwill be understood of course that the invention is not limited theretosince many obvious modifications can be made and it is intended toinclude within this invention any such modifications as will fall withinthe scope of the appended claims.

Having now described the invention, I claim.
 1. A method for inhibitingthe crystallization or precipitation of lactose from whey whichcomprises contacting the whey with a bisulfite moiety to form awater-soluble addition product of lactose and said bisulfite moiety. 2.A method for preparing a condensed whey product which is stable tosedimentation, which comprises:(a) treating whey with a bisulfite moietyto form an addition product of lactose and said bisulfite moiety, (b)removing water from said treated whey, and (c) recovering a condensedwhey having a solids content of at least 35 percent, by weight.
 3. Themethod defined in claim 2 wherein said bisulfite moiety is provided by awater soluble salt selected from the group consisting of ammonium,alkali metal and alkaline earth metal bisulfites.
 4. The method of claim3 wherein said water soluble salt is sodium bisulfite.
 5. The method ofclaim 3 wherein said water soluble salt is ammonium bisulfite.
 6. Themethod of claim 2 wherein said bisulfite moiety is provided by passinggaseous SO₂ through said whey.
 7. The method of claim 6 wherein NH₃ ispassed through said whey simultaneously with or prior to said SO₂. 8.The method of claim 2 wherein said whey is treated at a temperature ofabout 100° to about 150° F.
 9. The method of claim 2 wherein saidbisulfite moiety is provided at a concentration of from about 1.0 toabout 1.2 moles of bisulfite per mole of lactose.
 10. The method ofclaim 2 wherein said water is removed by heating under vacuum to recovera condensed whey having about 40 to about 50 percent solids, by weight.11. A method for preserving acidic feedstocks from spoilage bymicroorganisms which comprises combining said acidic feedstock with aspoilage inhibiting amount of a lactose-bisulfite addition product.